Question

If I m trying to find out if an object is a type of a certain class (or any of that class s descendants), it seems that I should use "isKindOf:"

if ([foo isKindOfClass:[bar class]]) {...}

But the compiler gives me a warning "invalid receiver type void * ".

This goes away if I cast "foo" to NSObject...or any other class! No matter what class I cast the object to, the code still works. That is, even if I do:

if ([(NSString *)foo isKindOfClass:[bar class]]) {...}

the "isKindOfClass" method still returns TRUE if and only if "foo" is of type "bar".

Am I missing something here? Shouldn t casting "foo" to another type make the logic fail? And why do I need to cast "foo" at all, since the whole point is that I m trying to figure out what type of object it is?

Answer 1

I m guessing you ve declared foo as:

void* foo;

void* is not an Objective-C type, so you can t send it messages like isKindOfClass.

Declare foo like this instead:

id foo;

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